Screw-type fastening device

ABSTRACT

A screw-type fastening device including a male threaded element such as a bolt and a female threaded element such as a nut in which each element contains a continuous helical root and crest disposed therein wherein the root and crest include V-shaped crests and V-shaped roots at an angle of 45°, respectively, external and internal chevron-shaped slots at angles of 90°, respectively, and three pairs of parallel load flanks, respectively, for easily releasing the threaded elements without abrasion and protecting them from self-lossensing from each other.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a Continuation-in-Part of application Ser.No. 07/097,837 filed on Sept. 17, 1987, which is now abandoned, which inturn is a Continuation-in-Part of application Ser. No. 06/941,189 filedon Dec. 12, 1986, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a screw-type fastening device such as abolt and nut, a bolt, casting screws, and the like and, moreparticularly, to a combined male and female threaded elements assemblywhich is shaped to swage crests of mating internal threads and therebyprovides an interference fit and prevailing torque that resistsself-loosening and protects the internal threads from abrading when thefastened male and female threaded elements are separated from eachother.

2. Description of the Prior Art

Many fastening devices such as a bolt and nut known in the art includemany types of continuous helical external and internal threads, such asfor example, triangular or rectangular thread configurations. Suchfastening devices are shown in U.S. Pats. Nos. 1,075,310 to Ulrich, No.2,215,770 to Sheffield, No. 3,661,194 to Macfarlane et al, No. 4,023,914to Holmes, No. 4,171,012 to Holmes, No. 4,341,497 to Downey et al, No.4,432,682 to McKewan, and No. 4,600,224 to Blose. However, there aremany problems with the prior art fastening devices. For example, it isdifficult to tightly fasten them and it is easy to loosen them afterfastening when the apparatus using such fastening devices is subjectedto continuous vibrations, movements and/or impacts because the male andfemale threaded elements are shaped with different configurations. Alsosuch fastening devices cannot prevent abrasion of the threaded portionswhen the fastened male and female elements are separated from eachother.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a newlyimproved screw-type fastening device.

Another object of the present invention is to provide a screw-typefastening device which includes V-shaped helical crests and roots havinga horizontal surface about an axis of male and female threaded elements,respectively, so that the male and female threaded elements can betightly fastened and do not loosen from each other.

A further object of the present invention is to provide a screw-typefastening device in which the male and female threaded elements includethe same configured helical threads so that each threaded element, suchas a bolt and a nut or a bolt and a screw casting, is protected fromabrasion of the surface of the threads thereof upon operation of thedevice.

Other objects and further scope of applicability of the presentinvention will become apparent from the detailed description givenhereinafter. It should be understood, however, that the detaileddescription and specific examples, while indicating preferredembodiments of the invention, are given by way of illustration only,since various changes and modifications within the spirit and scope ofthe invention will become apparent to those skilled in the art from thisdetailed description.

Briefly described, the present invention is related to a screw-typefastening device which comprises a male threaded element such as a boltand a female threaded element such as a nut in which each elementcontains continuous helical external and internal threads disposedtherein. The external and internal threads compose V-shaped crests adV-shaped roots at an angle of 45°, respectively, external and internalchevron-shaped slots at angles of 90°, respectively, and three pairs ofparallel load flanks, respectively, for releasing without abrasion andpreventing self-loosening.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the bolt and nut of the present invention fasteningtogether two workpieces.

FIG. 2 shows an enlarged view of the bolt and nut connection of FIG. 1.

FIG. 3 shows the bolt and nut threads separated.

FIG. 4 shows an enlarged view of a single thread of the bolt of FIG. 3.

FIG. 5 shows a partial sectional view of the bolt.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now in detail to the drawings for the purpose of illustratingpreferred embodiments of the present invention, the screw-type fasteningdevice as shown in FIGS. 1 and 2 comprises a male threaded element suchas a bolt 10 and a female threaded element such as a nut 11 adapted toreceive the male threaded element 10 for forming a joint. The bolt 10includes a bolt head 12, a shank 13, a continuous helical root 18, and acontinuous helical crest 19. The nut 11 includes the continuous helicalcrest 19' and a continuous helical root 18'.

As shown FIGS. 2, 3, and 4, thus, the bolt 10 includes the continuoushelical root 18 and crest 19 having an angle α of 45°, respectively. Onesurface disposed between the root 18 and crest 19 includes three loadflanks 20, 21, and 22. The load flanks 20 and 22 are a perpendicularsurface and the load flank 21 is a oblique surface about an axis 26 ofthe bolt 10. Angles β formed between the load flanks 20 and 21, andbetween the flanks 21 and 22 are a 135°, respectively. The other surfacedisposed between the crest 19 and root 18 includes three load flanks 23,24, and 25. The load flanks 23 and 25 are parallel surfaces and the loadflank 24 and 21 are parallel surfaces about the axis 26 of the bolt.Also angles γ formed between the load flanks 23 and 24, and between theload flanks 24 and 25 are 90°, respectively. The bolt head 12 isprovided with at least one pocket 27 for mating with the conventionalcorresponding screwdrivers (FIG. 5). The nut 11 is provided with thesame elements 18-25 having the same angles α-γ as on the bolt 10 foreffectively mating with the bolt 10.

In operation, after the bolt 10 having the continuous helical root 18and crest 19 extends through aligned apertures 15 in plates 14, the nut11 having the continuous helical root 18' and crest 19' is screwed tothe bolt 10 for clamping the plates 14 together. At this time, thehorizontal load flanks 20' and 22' with the smooth slant load flanks 21'about the axis 26 of the nut 11 can be effectively mated with thehorizontal load flanks 20 and 22 with the smooth slant load flanks 21about the axis 26 of the bolt 10 so that the nut 11 is smoothly screwedto the bolt 10.

Furthermore, the parallel oblique load flanks 23' and 25' of the nut 11,which are directed to the bolt head 12 of the bolt 10 are slidablyaccelerated to screw into the bolt 10. However, after the nut 11 isfastened into the bolt, the angles γ of 90° formed between the loadflanks 23' and 24' of the nut 11 are completely fixed into the angles γof 90° formed between the load flanks 23 and 24 of the bolt 10 forpreventing the nut 11 from loosening from the bolt 10. Furthermore, thecrests 19' of the nut 11 are tightly engaged into the roots 18' of thebolts for effectively accelerating the joining of these together. Thusthe nut 11 cannot loosen itself when the nut is subjected to thevibrations, movements and/or impacts of an apparatus including the nutsince it utilizes the screw-type fastening device of the presentinvention having the load flank angles γ of 90°. Also, upon releasingthe nut 11 from the bolt, using the conventional tools, the nut 11 canbe easily released from the bolt 10 since the angles γ are 90° and thefriction force of the tool can release the nut 11 from the bolt 10.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included in the scope of the following claims.

What is claimed is:
 1. A screw-type fastening device comprising:male andfemale threaded elements each having a continuous helical root and acontinuous helical crest, respectively, said continuous helical root andcrest including: a plurality of alternating crests and roots formedabout an axis of said male and female threaded elements, wherein saidcrests and roots are provided with, a first surface formed between eachof said crests and roots, said first surface having first and thirdhorizontal load flanks perpendicular to said axis and a second obliqueload flank disposed thereinbetween so that said second oblique loadflank forms angles of 135° and 225° with said first and third horizontalload flanks, respectively, a second surface formed between said crestsand roots having fourth and sixth oblique load flanks formed oblique tosaid axis and parallel to each other and a fifth oblique load flankdisposed thereinbetween so that said fifth oblique load flank formsangles of 90° and 270° with said fourth and sixth oblique load flanks,respectively, and so that said fifth oblique load flank is parallel tosaid second oblique load flank, and wherein the angle formed betweensaid first surface and said second surface is about 45°, whereby themale threaded element is effectively fastened into the female threadedelement, is easily released from the female threaded element withoutabrasion thereof, and prevents against loosening from the femalethreaded element due to vibration.
 2. The screw-type device of claim 1,wherein the male threaded element is a bolt.
 3. The screw-type device ofclaim 1, wherein the female threaded element is a nut.
 4. The screw-typedevice of claim 1, wherein the male threaded element is a screw.
 5. Thescrew-type device of claim 1, wherein the male threaded element is acasting screw.
 6. The screw-type device of claim 2 or 4, wherein themale threaded element is provided with a pocket disposed in said bolthead thereof for receiving a tool.